Automatic tensioning apparatus and method of use

ABSTRACT

An automatic tensioning apparatus is provided that includes a tensioning drive unit having: a longitudinally extending stationary base frame with a plurality of guides extending between a lower portion and an upper portion, and a plurality of rotatable feed wheels axially secured at the lower portion, as well as a translatable drive frame slidably coupled to the plurality of guides with a drive assembly coupled to the drive frame, the drive assembly including a drive motor and a tensile member interface for engaging and rotationally translating a tensile member. The tensioning drive unit further including a plurality of drive frame actuators actuatable to move the drive frame between a bottom frame position and a top frame position, as well as a sensor for at least indirectly sensing the position of the drive frame along a longitudinal base frame axis.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent Appl. No.63/198,537 filed on Oct. 26, 2020, the disclosure of which isincorporated herein by reference in its entirety for all purposes.

FIELD OF THE INVENTION

The invention relates generally to the field of floor cleaning systems.More particularly, the invention relates to a tensioning apparatus for afloor cleaning system.

BACKGROUND

Floor cleaning systems, such as barn alley scrapers, and other shuttlingcircuits are commonly used to move animal waste and other debris out ofan alley and into debris channels. Many such systems include a circuitformed by one or more shuttled scrapers connected to a motor via chain,wire rope, or braided rope (i.e., tensile members). Activation of themotor causes the scrapers to move along a chosen path that leads to oneor more debris channels. The circuit generally includes several guidesto change direction of the tensile member, often forming a rectangularconfiguration. The tensile member is subjected to a variable load thatgenerally increases as the scraper(s) engage an increased debris load,causing the tensile member to stretch and cause slack to occur.

Typical systems include components for driving the tensile member. Thesedrive systems usually consist of an A/C motor, multiple reductionsthrough belt and pulley, gearboxes, etc., which are coupled to asprocket or wrapped drum to engage the tensile member directly. Theslack produced by wear and/or stretching in these systems should beaccounted for to properly provide the required amount of tension todrive the load, and consists of excess length of tensile member thatmust be taken up by the driving motor before any movement of an attachedcleaning device will occur. One method of removing slack is to move theposition of the driving sprocket until the tensile member is undertension to the point that rotation of the motor will immediately causemovement of one or more cleaning devices.

For optimal system performance and longevity, proper tension includes abalance between not enough and too much. Not enough tension affects theability of the drive unit to properly drive the tensile member. This maycause skipping of sprocket teeth, which can cause high impact loading onthe drive system, or a sliding without rolling condition which increasessurface wearing on system corner guides, and on the tensile member, itcan further cause tangling or mis-winding on cable/rope systems andballing of excess chain that can lock the system up. If too much tensionis provided, then one result is wasted energy that goes into producinghigher loads on the drive system and the other components of thecircuit, which reduces life of the system components. Another result oftoo much tension is extra wear and/or stretching of the tensile member.This consumable tensile member is a relatively expensive consumable inthe system must be maintained by removing sections of the tensile memberwhen the available amount of tensioning capacity is fully utilized. Itis known in the prior art that this process of managing the excess slackand managing the “proper” tension is cumbersome and sometimesunpredictable.

A variety of mechanical tensioning systems are known, but include manydeficiencies. One such example of a known mechanical tensioner mechanismconsists of a moveable drive frame that is able to slide up and down ona vertical frame. The drive unit, which supports the tensile member, issupported by a mechanical tensioning unit consisting of a frame with alead-screw, commonly of ACME thread, which provides the ability tomanually slide the moveable drive frame up and down. To provide moretension to the tensile member, the operator must turn the lead screw, orlead screw nut, by hand to raise it up. To reduce tension, the nut orscrew is rotated the opposite direction to lower the unit down. As thereis very little feedback as to know when the tension is too much or toolittle it is up to the operator's impression of the correct tension toapply. In most cases the operator will tension the unit so that thetensile member does not ball up on the slack side of the circuit. Oncethe slack side is moving most operators will induce as much tension(preload) as possible to allow the circuit to run the longest possiblewithout additional tension being added. In this situation, the operatoris not providing the optimum tension for extended length and life of themachine. Instead, the operator is choosing to reduce life of themechanical components in order to save the time of continuallytensioning the circuit. Another example of a known tensioning systemutilizes the same concept as previously described but in-lieu of a leadscrew to drive the moveable frame, a hydraulic or pneumatic cylinder(s)does the work of moving the drive frame up or down. The improvement ofutilizing hydraulics as a method for tensioning allows for meaningfulfeedback to the operator as to how much tension is being applied. Thisfeedback is relayed to the operator through gauges which read thepressure in the hydraulic circuit. With a system such as this it is nowpossible to always set the tensioner to a certain pressure in order toget a desired and repeatable preload on the circuit.

Two types of known hydraulic systems in tensioning system can beutilized. The first is a hydraulic or pneumatic system consisting of ahand pump. The operator will manually bring the tensioner system up topressure with the hand pump. Over time however, the system will havelosses. Losses to pressure usually occur due to the wear and/orstretching of the tensile members. Additional losses come from thehydraulic/pneumatic circuit leaking or bleeding to the tank. When thisoccurs, the manual hydraulic/pneumatic system will require repumping tobring the system back to the desired pressure. This is burdensome on theoperators and requires constant monitoring and user input. The secondtype of hydraulic/pneumatic system adds an electric pumping system thatcontinually brings the system to a desired pressure. This improvementreduces the need for the operator to maintain the system.

Where the known hydraulic/pneumatic tensioner system fails is in thefact that the system is preloaded to the maximum required tension neededfor the tensile member to complete its circuit. In the field of theinvention these cleaning/scraping circuits build load over their runcycle. When the cleaning/scraper cycle starts, there is little to noload (requiring the least amount of pretension), as the debris iscollected the tensile member will require more tension to drive theincreasing load. Thus, the preload being added to the circuit shouldalways be what is required at the maximum load of the system which onlyoccurs at the end of the cycle. In addition, the known tensioningmethodology also fails to provide optimal preload to the system due tothe fact that the wasted preload at the beginning of a cleaning/scrapingcycle is once again adding to the wear/stretch of the tensile member, aswell as wear and strain on the drive system and other mechanicalcomponents.

Lastly, another known tensioner system is disclosed in U.S. Pat. No.9,284,126 entitled “Automatic Scraper Chain Tensioning Apparatus.” Thedisclosed invention utilizes multiple springs, idler rollers, andadditional mechanisms on top of the traditional tensioning methodslisted previously. The added bends and twists to the tensile memberthrough these mechanisms inherently induces wear and stress on thetensile members due to the constant bending and change of tensile memberdirection. Additionally, the added mechanical components of idlerrollers, bearings, springs, etc. lend themselves to additionalmaintenance, and the invention can be limited by the available andchosen size, shape, and spring constants for the mechanical springs.

It will be understood by those skilled in the art that one or moreaspects of this invention can meet certain objectives, while one or moreother aspects can lead to certain other objectives. Various objects,features, benefits and advantages of the invention will be apparent inthis summary and descriptions of the disclosed embodiment, and will bereadily apparent to those skilled in the art. Such objects, features,benefits and advantages will be apparent from the above as taken inconjunction with the accompanying figures and all reasonable inferencesto be drawn therefrom.

SUMMARY OF THE INVENTION

In at least some embodiments, an automatic tensioning apparatus isprovided that includes a tensioning drive unit comprising: alongitudinally extending stationary base frame with a plurality ofguides extending between a lower portion and an upper portion, and aplurality of rotatable feed wheels axially fixed at the lower portion; atranslatable drive frame slidably coupled to the plurality of guides; adrive assembly secured to the drive frame, and including a drive motorand a tensile member interface for engaging and rotationally translatinga tensile member; a plurality of drive frame actuators coupled to thedrive frame, actuatable to move the drive frame between a bottom frameposition and a top frame position, each situated between the lowerportion and upper portion of the base frame; and a sensor for at leastindirectly sensing the position of the drive frame; and a controller incommunication with the tensioning drive unit to provide activationsignals to the drive motor and the plurality of drive frame actuatorsbased at least in part on the position of the drive frame.

In at least some other embodiments, a floor cleaning system having acircuit that includes a tensile member and a floor scraper is provided,the floor cleaning system including: a tensioning apparatus comprising:a tensioning drive unit comprising: a longitudinally extendingstationary base frame with a plurality of guides extending between alower portion and an upper portion, and a plurality of rotatable feedwheels axially fixed at the lower portion; a translatable drive frameslidably coupled to the plurality of guides; a drive assembly secured tothe drive frame, and including a drive motor and a tensile memberinterface for engaging and rotationally translating the tensile member;a plurality of drive frame actuators coupled to the drive frame,actuatable to move the drive frame between a bottom frame position and atop frame position, each situated between the lower portion and upperportion of the base frame; and a sensor for at least indirectly sensingthe position of the drive frame; and a controller in communication withthe tensioning drive unit to provide activation signals to the drivemotor and the plurality of drive frame actuators based at least in parton the position of the drive frame.

In at least some other additional embodiments, a tensioning drive unitis provided that includes a longitudinally extending stationary baseframe having a lower portion and an upper portion, a translatable driveframe slidably coupled to the base frame; a drive assembly secured tothe drive frame, and including a drive motor and a tensile memberinterface for engaging and rotationally translating a tensile member;and a plurality of drive frame actuators coupled to the drive frame,actuatable to move the drive frame between a bottom frame position and atop frame position, each situated between the lower portion and upperportion of the base frame.

In at least some further embodiments, an automatic tensioning apparatusis provided that includes a tensioning drive unit comprising: alongitudinally extending stationary base frame with a plurality ofguides extending between a lower portion and an upper portion, and aplurality of rotatable feed wheels axially secured at the lower portion;a translatable drive frame slidably coupled to the plurality of guides;a drive assembly coupled to the drive frame, and including a drive motorand a tensile member interface for engaging and rotationally translatinga tensile member; a plurality of drive frame actuators actuatable tomove the drive frame between a bottom frame position and a top frameposition; and a sensor for at least indirectly sensing the position ofthe drive frame along a longitudinal base frame axis.

In at least yet some other embodiments, a floor cleaning system having acircuit that includes a tensile member and a floor scraper is provided,the system comprising: a tensioning drive unit comprising: alongitudinally extending stationary base frame with a plurality ofguides extending between a lower portion and an upper portion, and aplurality of rotatable feed wheels axially secured at the lower portion;a translatable drive frame slidably coupled to the plurality of guides;a drive assembly coupled to the drive frame, and including a drive motorand a tensile member interface for engaging and rotationally translatinga tensile member; a plurality of drive frame actuators actuatable tomove the drive frame between a bottom frame position and a top frameposition; and a sensor for at least indirectly sensing the position ofthe drive frame along a longitudinal base frame axis; and a controllerin communication with the tensioning drive unit to provide activationsignals to the drive motor and the plurality of drive frame actuatorsbased at least in part on the position of the drive frame.

In still yet another embodiment, a method of use for an automatictensioning apparatus is provided comprising: positioning a drive frameand drive assembly, movably coupled to a longitudinally extendingstationary base frame, in a bottom adjustment position along the baseframe using a plurality of drive frame actuators coupled to the driveframe and base frame, wherein a tensile member is rotationally engagedwith the drive assembly to provide translation of the tensile member;actuating the plurality of drive frame actuators to cause verticaltranslation of the drive frame to remove slack in the tensile member,wherein the tensile member forms part of a continuous circuit engaging aplurality of movable cleaning devices; storing as a minimum pressure, asensed pressure exerted to extend the plurality of drive frame actuatorsto remove the slack; continue actuating the actuators until the sensedpressure has exceeded the minimum pressure, storing a detected currentposition of the drive frame relative to the base frame as a targetposition, and the minimum pressure as a minimum preload pressure;activating a cleaning cycle that includes rotating a drive motor of thedrive assembly in a first rotational direction to move the plurality ofmovable cleaning devices in a first longitudinal direction; comparingthe detected current position of the drive frame with the targetposition, if the detected current position is at or below a pre-definedmaximum lower offset position measured from the target position, thenactuate the plurality of drive frame actuators to move the drive frameto the target position; and detecting completion of the cleaning cycleand updating the target position value that is stored to be equal to thedetected current position.

Other embodiments, aspects, and features of the invention will beunderstood and appreciated upon a full reading of the detaileddescription and the claims that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are disclosed with reference to theaccompanying drawings and are for illustrative purposes only. Theinvention is not limited in application to the details of construction,or the arrangement of the components illustrated in the drawings. Theinvention is capable of other embodiments and/or of being practiced orcarried out in other various ways.

FIG. 1 is a top perspective view of an exemplary floor cleaning systempositioned relative to an exemplary barn floor and wall. The floorcleaning system including an exemplary automatic tensioning apparatuscomprising a tensioning drive unit, a controller, and a junction box.

FIG. 2 is a front perspective view of the tensioning drive unit of FIG.1.

FIG. 3 is a rear perspective view of the tensioning drive unit.

FIG. 4 is an exploded perspective view of the tensioning drive unit.

FIG. 5 is front perspective view of an exemplary drive frame and driveassembly of the tensioning drive unit of FIG. 1.

FIG. 6 is front perspective view of the drive assembly.

FIG. 7 is a front view of the tensioning drive unit coupled with anexemplary tensile member.

FIG. 8 is a top view of the tensioning drive unit coupled with thetensile member.

FIG. 9 is a cross-sectional front view of the tensioning drive unittaken along line 9-9 of FIG. 8.

FIG. 10 is front perspective view of the tensioning drive unit andtensile member of FIG. 7 with the front cover of the tensioning driveunit removed for illustrative purposes, showing the drive frame in a topframe position.

FIG. 11 is side view of the tensioning drive unit and tensile member ofFIG. 10

FIG. 12 is top view of the tensioning drive unit and tensile member ofFIG. 10.

FIG. 13 is a cross-sectional view of the tensioning drive unit takenalong line 13-13 of FIG. 12.

FIG. 14 is front perspective view of the tensioning drive unit andtensile member with the front cover of the tensioning drive unit removedfor illustrative purposes, showing the drive frame in a bottom frameposition.

FIG. 15 is side view of the tensioning drive unit and tensile member ofFIG. 14

FIG. 16 is top view of the tensioning drive unit and tensile member ofFIG. 14.

FIG. 17 is a cross-sectional view of the tensioning drive unit takenalong line 17-17 of FIG. 16.

FIG. 18 is a flow chart 300 illustrating an exemplary method of usingthe automatic tensioning apparatus.

DETAILED DESCRIPTION

FIG. 1 illustrates an exemplary floor cleaning system 100 positionedrelative to a wall 102 and a floor 104. The wall 102 and floor 104 areexemplary and are provided for illustrative purposes to show the layoutof an exemplary barn floor cleaning configuration. For clarification,the wall 102 and floor 104 are not considered part of the floor cleaningsystem 100 itself, but serve as structure with which the floor cleaningsystem 100 can be implemented therewith. As shown in FIG. 1, the floor104 includes two exemplary longitudinal parallel alleys 106, each havinginterconnected cleaning devices, such as floor scrapers 108 situated atleast partially within the alley 106 and positioned to direct debrisinto a debris channel 107. The scrapers 108 are further coupled by atensile member 110 to form a circuit 111 (i.e., a continuouscircuit/loop of connections). The tensile member 110 can include variousindividual lengths (e.g., coupled between scrapers 108, etc.) or acontinuous loop coupled to the scrapers 108. For simplicity, the termtensile member 110 used herein can refer to either configuration.Further, the tensile member 110 can take many forms such as a chain, arope, a cable, etc. A plurality of roller guides 112 are provided at thecorners to change the direction of the tensile member 110 accordingly.The roller guides 112 are secured in position (e.g., to the floor 104)and unlike the scrapers 108, remain anchored in place during operationof the floor cleaning system 100. The tensile member 110 is fixedlysecured to the scrapers 108, but allowed to rotate along the rollerguides 112.

The floor cleaning system 100 further includes an exemplary automatictensioning apparatus 116, that in at least some embodiments, comprisesan exemplary tensioning drive unit 120, a controller 122, and one ormore junction boxes 124. The tensioning drive unit 120 provides a meansto move/translate and properly tension the tensile member 110. When thetensioning drive unit 120 is activated to move the tensile member 110,the coupled scrapers 108 are also moved along the alleys to push wasteand debris. As the floor cleaning system 100 shown in FIG. 1 isexemplary, it shall be understood that the quantity and positioning ofvarious components, such as the scrapers 108, tensile member 110, rollerguides 112, etc. can vary to accommodate a desired circuit shape andconfiguration.

Referring to FIGS. 2 and 3, the exemplary tensioning drive unit 120 fromFIG. 1 is shown in front and rear perspective views, while FIG. 4provides an exploded view of the tensioning drive unit 120. Thetensioning drive unit 120 includes a longitudinally extending stationarybase frame 126 that provides primary structural support. The base frame126 includes a lower portion 130 and an upper portion 134. The baseframe 126 further includes a first side wall 136 and a second side wall138 extending between the lower portion 130 and the upper portion 134,wherein the sidewalls include a plurality of guides. In at least someembodiments, the plurality of guides can include a first guide 140extending longitudinally along the first side wall 136 and a secondguide 142 extending longitudinally along the second side wall 138. In atleast some embodiments, the guides can take the form of slots, and canbe reinforced with longitudinally extending inner or outer slottedreinforcement portions, such as reinforcement portions 144.

The tensioning drive unit 120 further includes a translatable driveframe 150. The drive frame 150 is slidably coupled to the guides 140,142 to allow the drive frame 150 to translate between the lower portion130 and the upper portion 134. In at least some embodiments, the driveframe 150 includes a plurality of rollers 152 rotatably secured to thedrive frame 150, wherein the rollers 152 are sized and shaped toslidingly engage with the guides 140, 142 such that the drive frame 150is restricted to move only longitudinally between the lower portion 130and the upper portion 134 along a fixed longitudinal base frame axis 172(see FIG. 7).

Secured to the drive frame 150 is a drive assembly 154 (see FIGS. 5 and6). The drive assembly 154 includes a drive motor 156 coupled with atensile member interface 158 that engages and translates the tensilemember 110, to move the associated circuit 111 (i.e., causing thescrapers 108 to move as desired). The tensile member interface 158 canvary in shape and size depending on the type of tensile member 110 it isintended to be engaged with. For example, when the tensile member 110 isa chain, the tensile member interface 158 can be a sprocket, and whenthe tensile member 110 is a cable or rope, the tensile member interface158 can be a wrapped drum, etc. In at least some embodiments, thetensile member interface 158 is circular.

In at least some embodiments, the drive assembly 154 can include variousother components, such as a motor mount 160, a belt and pulley reductionassembly 162, a gearbox reduction 166, and an encoder wheel 168, whilein other embodiments, less or more components can be included. As shownin the figures, the drive assembly 154 is secured to the drive frame 150such that the tensile member interface 158 (and encoder wheel 168)rotates about a drive axis 170 that extends perpendicular to thelongitudinal base frame axis 172.

The drive frame 150 is translatable between the lower portion 130 andthe upper portion 134 of the base frame 126 using a plurality of driveframe actuators 174 coupled therewith. In at least some embodiments, thedrive frame actuators 174 include telescopic hydraulic cylinders 175,while in other embodiments, any of various other known types ofactuators can be utilized, such as pneumatic actuators, electric linearactuators, non-telescopic hydraulic cylinders, etc. The drive frame 150can be adapted to utilize various types and quantities of drive frameactuators 174 including one actuator, or two or more actuators.

As noted above, the base frame 126 is stationary and configured to besecured in place, such as to the floor 104. In at least someembodiments, the base frame 126 includes a bottom mounting plate 176 forsecurement to the floor 104. The base frame 126 can also include aplurality of tensile member feed wheels 178 rotatably secured to wheelsupports 179 on the base frame 126. The wheel supports 179 include axialwheel mounts 180.

When hydraulic drive frame actuators 174 are utilized, a hydraulicsystem 182 can be provided for actuating the drive frame actuators 174.The hydraulic system 182 can be mounted to the drive frame 126 as partof the tensioning drive unit 120 or can be mounted remotely and coupledto the tensioning drive unit 120. In at least some embodiments, thehydraulic system 182 includes a 184 mount, an electric pump 186, areservoir 188, a hydraulic control valve block 189, a dump valve 190, aproportional relief valve 192, a pressure transducer 194, an accumulator196, and a pressure gauge 198, along with various interconnections (e.g.rigid lines, hoses, fittings, etc.), while in other embodiments, less ormore components can be included.

FIGS. 7 and 8 provide front and top perspective views of the tensioningdrive unit 120 engaged with a tensile member 110. For illustrativepurposes, only a portion of the tensile member 110 is shown, further thetensile member 110 is shown as a chain and the tensile member interface158 is shown as a sprocket. FIG. 9 is a cross-sectional view of thetensioning drive unit 120 taken along line 9-9 of FIG. 8 showing thetensile member 110 extending horizontally and entering the tensioningdrive unit 120 and engaging with the feed wheel 178 at the entrance toredirect the tensile member 110 upwards to the tensile member interface158 and wrapping thereover, then extending downward to the other feedwheel 178 at the exit, and being redirected out along the horizontal.This configuration allows the tensile member 110, which typicallyextends along the floor 104 (e.g., horizontal) to enter and leave at thesame level, although the position and quantity of the feed wheels 178could vary to accommodate different entry and exit heights, and loadrequirements.

Referring to FIGS. 10-12, front perspective, side, and top views of thetensioning drive unit 120 and tensile member of FIG. 7 are provided withthe front cover 202 of the tensioning drive unit 120 removed forillustrative purposes. FIG. 13 provides a cross-sectional view of thetensioning drive unit 120 taken along line 13-13 of FIG. 12. As seen inFIGS. 11-13, the drive frame actuators 174 are fully extended to placethe drive frame 150 in a top adjustment position 204 along the baseframe axis 172, situated near the top, at a distance D1 from the bottommounting plate 176.

Referring to FIGS. 14-16, front perspective, side, and top views of thetensioning drive unit 120 and tensile member are provided with the frontcover 202 of the tensioning drive unit 120 removed for illustrativepurposes, similar to FIGS. 10-12, but with the drive frame repositioned.FIG. 17 provides a cross-sectional view of the tensioning drive unit 120taken along line 17-17 of FIG. 16. As seen in FIGS. 14-17, the driveframe actuators 174 are no longer fully extended, but are retracted toplace the drive frame 150 in a bottom adjustment position 206 along thebase frame axis 172, situated near the bottom, at a distance D2 from thebottom mounting plate 176.

The tensioning drive unit 120 further includes at least one sensor 208(e.g., FIG. 14) configured to at least indirectly monitor the positionof the drive frame 150 relative to the base frame 126, as this can beaccomplished in numerous ways, the sensor 208 can take many forms. Forexample, the sensor can be an ultrasonic distance sensor (FIG. 13)positioned on the base frame 126 above the drive frame 150. In otherembodiments, the sensor can be located in other locations and utilizeother known technologies, such as laser, proximity, photoelectric, fiberoptic, etc. Further, in at least some embodiments, the term sensor canbe construed to include another component that can provide positionsensing indirectly.

Referring to FIGS. 13 and 17, raising or lower the drive frame 150provides increased or decreased tension to a coupled tensile member 110connected in the circuit 111 that has a fixed length, resulting in adecrease or increase in slack. Raising and lowering of the drive frame150 is performed by the plurality of drive frame actuators 174 based oncontrol signals received from the controller 122 (FIG. 1) incommunication with the tensioning drive unit 120.

The controller 122 provides control of the tensioning drive unit 120 tooperate the floor cleaning system 100. As the automatic tensioningapparatus 116 can utilize various hydraulic, electric, and/or pneumaticdevices, one or more junction boxes 124 can be utilized to facilitatesupply and/or distribution thereof, as such it should be understood thatthese components can be mounted in various locations and include varioustypical interconnecting lines, hoses, cables, wires, etc. to distributethese resources. In at least some embodiments, the drive motor 156 iscontrolled by a Variable Frequency Drive (VFD), which can be housed withthe controller 122. For reference, the bottom adjustment position 206along the base frame axis 172 can be considered a zero point on the baseframe axis 172, with a height value along the base frame axis 172increasing in value as it extends to the top adjustment position 204.

The controller 122 can communicate with the tensioning drive unit 120and a user to send and receive commands and information to operate thetensioning drive unit 120. The controller 122 can be housed in aplurality of boxes and in at least some embodiments, includes aProgrammable Logic Controller (PLC) and a Human Machine Interface (HMI),such as a PLC model no. FX5UC-32MT/DSS-TS and an HMI model no.GT2105-QTBDS, both manufactured by Mitsubishi. In other embodiments, thecontroller 122 can include any of various types of processor-driven I/Oconfigurations capable of providing the described operations.Communication with the PLC and HMI can occur via various known methods,such as direct link, remote link, touchscreen, etc. and can utilizevarious software programs and/or protocols to effectuate the desiredoperation. The HMI provides a user interface between the user and thecontroller 122 and in at least some embodiments, can include a local orremote screen/interface, wherein the user can enter various pre-selectedvalues (e.g., height values) to be utilized during the operation of thetensioning drive unit 120. In at least some embodiments the HMI canmerely include various buttons, dials, switches, etc. actuatable by auser to effectuate operation of the automatic tensioning apparatus 116as desired. The PLC can further include memory for storing values. Thecontroller 122 can include internal memory for storing positionalvalues, and/or be in communication with an external memory (e.g., harddrive, RAM, etc.)

Referring back to FIG. 1, the tensile member 110 is coupled to scrapers108 to form a circuit 111. To move the scrapers 108 the drive assembly154 is activated by the controller 122. Moving the scrapers 108 in afirst direction requires the tensile member 110 to be translated throughthe tensioning drive unit 120 via activation of the drive assembly 154to rotate the tensile member interface 158 in a first rotationaldirection to pull the tensile member 110 in and to pass it back out.Activation of the drive assembly 154 to rotate the tensile memberinterface 158 in a (opposite) second rotational direction causes thetensile member 110 to be pulled into the tensioning drive unit 120 onthe opposite side and passed out.

The automatic tensioning apparatus 116 is configured to monitor tensionon the tensile member 110 as it rotates the circuit 111 moving thescrapers 108. As discussed above, too much tension creates excessivestrain on the system and too little tension allows for excessive slack,which also creates excessive strain on the system. As such it isdesirable to maintain a “proper” level of tension between the extremes.To monitor the amount of tension on the tensile member 110, the downwardforce 210 (FIG. 14) being imparted to the tensile member interface 158can be identified using various methods. One such method is to monitorthe system pressure being exerted on the drive frame actuators 174 thatsupport the drive frame 150 and resist the downward force 210, which inat least some embodiments, is the pressure measured at the pressuretransducer 194 and/or pressure gauge 198 of the hydraulic system 182used to extend and retract the drive frame actuators 174.

Referring to FIG. 18, a flow chart 300 is provided illustrating anexemplary method of using the automatic tensioning apparatus 116 toautomatically tension the tensile member 110 in the floor cleaningsystem 100 having the circuit 111 that includes one or more scrapers 108coupled to the tensile member 110. The method/process begins at step302, with the drive frame 150 in the bottom adjustment position 206 (atthe lowest available point ((zero point)) on the base frame axis 172).In this position, tensile member 110 has extra slack in the circuit 111.At step 304, the plurality of drive frame actuators 174 are actuated tobegin moving the drive frame 150 along the base frame axis 172 andtowards the top adjustment position 204 to place the tensile member 110under minimum tension at a height value greater than zero along the baseframe axis 172. In embodiments where the drive frame actuators 174 arehydraulically driven, the controller 122 activates the electric pump 186to deliver hydraulic fluid from reservoir 188 to the drive frameactuators 174. Fluid enters the hydraulic cylinders 175 of the driveframe actuators 174 filling the void volume; once the void volume withinthe cylinders are filled pressure begins to build in the hydraulicsystem 182 until a minimum pressure is provided sufficient enough tobegin translating the drive frame 150 along the base frame axis 172.This change in position of the drive frame 150 along the base frame axis172 is monitored by the sensor 208. The drive frame 150 will continue toraise at this same minimum pressure until the slack in the tensilemember 110 is taken up. Once the slack in tensile member 110 is removed,drive frame actuator pressure will begin to increase as measured bypressure transducer 194, as queried at step 306. At this point whendrive frame actuator pressure begins to rise, it is understood that thesystem is now adding unwanted and unneeded preload force.

At step 308, once pressure is sensed as increasing past the minimumpressure (noting an acceptable tolerance), the controller 122 recordsthe current position (i.e., current height value) of the drive frame 150along the base frame axis 172 and logs it as the “target position”(i.e., target height value) for drive frame 150 for the next cycle. Italso records the applied minimum pressure and saves it as “minimumpreload pressure.”

At step 310, a cleaning/scraping cycle begins by activating the drivemotor 156 to begin translating the tensile member 110 through thetensioning drive unit 120. The cleaning cycle is configured to move thecleaning devices for a set period of time, although various other oradditional criteria could be used to determine the duration of thecleaning cycle. As debris is collected on the scrapers 108 passing alongthe floor 104, the tension on the tensile member 110 increases due tothe added debris load. This creates a downward force 210 on the driveframe 150. This force will soon overcome the “minimum preload pressure”provided by the drive frame actuators 174 that was taking-up the excessslack in the tensile member 110 prior to the system starting thecleaning cycle. At this point, the drive frame 150 “current position”will begin to move lower (i.e., reduced height value) as identified bythe sensor 208. The controller 122 monitors the “current position” ofthe drive frame 150 as indicated in step 312 and will allow the “currentposition” to continue moving down the base frame axis 172 from the“target position” to a user defined position on the base frame axis 172called the “maximum lower offset.” This “maximum lower offset” value isindicative of the amount of additional slack in the tensile member 110that is deemed acceptable without causing mechanical problems, such asballing of the chain or rope on the slack side.

At step 314 the current position is compared with the “maximum loweroffset,” if the “current position” (i.e., current high value) of thedrive frame 150 is positioned on the base frame axis 172 at or below the“maximum lower offset,” then at step 316, the controller 122 commandsincreased pressure to the drive frame actuators 174 by activating theelectric pump 186 to increase system pressure to move the drive frame150 to an increased height value. Pressure to the drive frame actuators174 will continue to be increased until the drive frame 150 “currentposition” equals or is greater than the “target position.” At thispoint, the pressure in the hydraulic system 182 will have increased. Toaccount for excessive overshoot of “target position,” the controller 122can include a provision for a user settable “maximum upper offset.” The“maximum upper offset” being the acceptable overshoot the drive frame150 moves above the “target position” along the base frame axis 172before the controller 122 will open the dump valve 190 to bleed offpressure to the drive frame actuators 174 resultingly lowering the“current position” of the drive frame 150, as seen in steps 318 and 320.Thus, the “maximum upper offset” and “maximum lower offset” provideconfigurable dead-bands to inhibit the controller 122 from constantlyrunning the electric pump 186 and then opening the dump valve 190. In atleast some embodiments, in addition to monitoring position of the driveframe 150 (i.e., the height value), a proportional relief valve 192 canbe set to an allowable “maximum pressure” for the safety of mechanicalcomponents in the event of the electric pump 186 does not shut off. Theaforementioned process continues until the until the end of the cleaningcycle is detected at step 322, which can be a pre-programmed instructionbased on time, scraper repetitions, user input, etc., further notingthat the status of the cleaning cycle (i.e., complete or not complete)can be continuously monitored along in combination with the currentposition of the drive frame and the maximum lower offset position.

When the cleaning cycle ends, the process advances to step 324 where thecontroller 122 stops the drive motor 156 and sets the proportionalrelief valve 192 to the “minimum preload pressure.” The pressure on thedrive frame actuators will then drop to the “minimum preload pressure.”When this occurs, “current position” of the drive frame 150 will drop toa new updated “target position” that is recorded by the controller 122in step 326. Over time, as the cleaning process is repeated, the “targetposition” value will continue to slowly increase as the tensile member110 wears/stretches, hence automatically compensating for chain/ropestretch and wear without user intervention. With the new updated “targetposition” set, the controller 122 in at least some embodiments, resetsthe proportional relief valve 192 back to a “maximum pressure” value atstep 328, and then waits at step 330 for a new cleaning cycle startcommand from the controller 122. The aforementioned process can beperformed in various other ways including more or less steps and invarying order.

Although the automatic tensioning apparatus 116 has been describedutilizing drive frame position (i.e., height value) as a feedbackmechanism to indicate the tension on the tensile member 110, variousother mechanisms can be utilized as discussed below. For example, aloadcell can be provided in-line with the tensile member 110, or on theshaft securing the tensile member interface 158, or on any of the rollerguides 112, or the axial wheel mounts 180, to measure tension in thetensile member 110 and equate the sensed load value to the requiredpressure in the hydraulic cylinders of the drive frame actuators 174 toprovide an equal and opposite upward force. Another example includesutilizing the amperage load on the drive motor 156 to calculate thetheoretical tension in the tensile member 110. This entails recordingthe minimum percent of output torque required with no load on thecircuit 111, the downward force 210 can be equated to a requiredpressure within the hydraulic cylinders of the drive frame actuators 174so as to equal the downward force 210 caused by the tensile member 110,hence providing the necessary tension to drive the load. The outputtorque can be calculated using the measured or known amperage andvoltage drawn by the motor as well as the rotational speed of the motorshaft (measured by the rotation of the encoder wheel 168, for example).The feedback loop would then constantly adjust pressure based on thepercent of output torque.

Yet another example includes using pressure feedback from the cylindersof the drive frame actuators 174. Using pressure differential between arod-side and cap-side of a cylinder piston in the drive frame actuator174, it is possible to control the system to provide the correct amountof tension. At no load, the controller 122 would pressurize the cylindersuch that the force on both the rod-side of the piston and the cap-sideof the piston is equal to zero by equation: [(Pressure on Cap-Side) x(Area of Cap-Side Piston)−(Pressure on Rod-Side)×(Area of Rod-SidePiston)=Force on Piston]. When the tensile member 110 sees a load, itwill induce a delta pressure which is measured by pressure transducerson both sides of the cylinder. The controller 122 would either add orremove pressure from the load bearing side of the cylinder to bring thesystem back to a zero state. The dead-band would be the allowabledifferential in pressure between the cap-side and rod-side of thecylinder.

In addition to the disclosed shapes and sizes, the aforementionedcomponents, can vary to include numerous adaptations. Further, thematerial composition of all components can also include numerouselements, such as steel, aluminum, alloys, plastics, etc. The use of theterm “plurality” in the description or claims shall be understood toinclude “one or more,” and the terms “bottom”, “top”, “upper” and“lower” shall not be considered limiting in that they are used forconvenience when referencing a vertical orientation of the invention,while other orientations of the invention have been contemplated.

Although the invention has been herein described in what is perceived tobe the most practical and preferred embodiments, it is to be understoodthat the invention is not intended to be limited to the specificembodiments set forth above. Rather, it is recognized that modificationsmay be made by one of skill in the art of the invention withoutdeparting from the spirit or intent of the invention and, therefore, theinvention is to be taken as including all reasonable equivalents to thesubject matter of the appended claims and the description of theinvention herein.

What is claimed is:
 1. An automatic tensioning apparatus comprising: atensioning drive unit comprising: a longitudinally extending stationarybase frame with a plurality of guides extending between a lower portionand an upper portion, and a plurality of rotatable feed wheels axiallysecured at the lower portion; a translatable drive frame slidablycoupled to the plurality of guides; a drive assembly coupled to thedrive frame, and including a drive motor and a tensile member interfacefor engaging and rotationally translating a tensile member; a pluralityof drive frame actuators actuatable to move the drive frame between abottom frame position and a top frame position; and a sensor for atleast indirectly sensing the position of the drive frame along alongitudinal base frame axis.
 2. The automatic tensioning apparatus ofclaim 1, wherein the drive assembly further includes a plurality ofrollers engaged with the plurality of guides.
 3. The automatictensioning apparatus of claim 1, wherein the plurality of drive frameactuators includes a pair of drive frame actuators, each includinghydraulic or pneumatic cylinders to provide actuation.
 4. The automatictensioning apparatus of claim 1, wherein a first of the plurality ofrotatable feed wheels engages the tensile member prior to engagementwith the tensile member interface and a second of the plurality ofrotatable feed wheels engages the tensile member after engagement withthe tensile member interface.
 5. The automatic tensioning apparatus ofclaim 4, wherein the first of the plurality of rotatable feed wheelsredirects the tensile member 90 degrees and directly to the tensilemember interface in a vertical orientation, and wherein the second ofthe plurality of rotatable feed wheels redirects the tensile member 90degrees from a vertical orientation as it extends directly from thetensile member interface.
 6. The automatic tensioning apparatus of claim4, further including a controller in communication with the tensioningdrive unit to provide activation signals to the drive motor and theplurality of drive frame actuators, based at least in part on theposition of the drive frame.
 7. The automatic tensioning apparatus ofclaim 5, wherein the first of the plurality of rotatable feed wheels andthe second of the plurality of rotatable feed wheels are the onlyrotatable feed wheels included in the plurality of rotatable feedwheels.
 8. The automatic tensioning apparatus of claim 2, wherein thetensile member interface is a sprocket having teeth to engage a tensilemember.
 9. The automatic tensioning apparatus of claim 1, wherein thetensile member interface rotates about a drive axis that extendsperpendicular to the longitudinal base frame axis.
 10. The automatictensioning apparatus of claim 9, further including an encoder wheel thatrotates with the tensile member interface about the drive axis.
 11. Theautomatic tensioning apparatus of claim 10, wherein the drive assemblyfurther includes a belt and pulley reduction assembly coupled to thedrive motor.
 12. The automatic tensioning apparatus of claim 9, whereinthe drive assembly further includes a gearbox reduction coupled betweenthe belt and pulley reduction assembly and the tensile member interface.13. The automatic tensioning apparatus of claim 9, further including acontroller in communication with the tensioning drive unit to provideactivation signals to the drive motor and the plurality of drive frameactuators, based at least in part on the position of the drive frame.14. A floor cleaning system having a circuit that includes a tensilemember and a floor scraper, the system comprising: a tensioning driveunit comprising: a longitudinally extending stationary base frame with aplurality of guides extending between a lower portion and an upperportion, and a plurality of rotatable feed wheels axially secured at thelower portion; a translatable drive frame slidably coupled to theplurality of guides; a drive assembly coupled to the drive frame, andincluding a drive motor and a tensile member interface for engaging androtationally translating a tensile member; a plurality of drive frameactuators actuatable to move the drive frame between a bottom frameposition and a top frame position; and a sensor for at least indirectlysensing the position of the drive frame along a longitudinal base frameaxis; and a controller in communication with the tensioning drive unitto provide activation signals to the drive motor and the plurality ofdrive frame actuators based at least in part on the position of thedrive frame.
 15. A method of use for an automatic tensioning apparatuscomprising: positioning a drive frame and drive assembly, movablycoupled to a longitudinally extending stationary base frame, in a bottomadjustment position along the base frame using a plurality of driveframe actuators coupled to the drive frame and base frame, wherein atensile member is rotationally engaged with the drive assembly toprovide translation of the tensile member; actuating the plurality ofdrive frame actuators to cause vertical translation of the drive frameto remove slack in the tensile member, wherein the tensile member formspart of a continuous circuit engaging a plurality of movable cleaningdevices; storing as a minimum pressure, a sensed pressure exerted toextend the plurality of drive frame actuators to remove the slack;continue actuating the actuators until the sensed pressure has exceededthe minimum pressure, storing a detected current position of the driveframe relative to the base frame as a target position, and the minimumpressure as a minimum preload pressure; activating a cleaning cycle thatincludes rotating a drive motor of the drive assembly in a firstrotational direction to move the plurality of movable cleaning devicesin a first longitudinal direction; comparing the detected currentposition of the drive frame with the target position, if the detectedcurrent position is at or below a pre-defined maximum lower offsetposition measured from the target position, then actuate the pluralityof drive frame actuators to move the drive frame to the target position;and detecting completion of the cleaning cycle and updating the targetposition value that is stored to be equal to the detected currentposition.
 16. The method of claim 15, further including a controller forstoring the activatable cleaning cycle instructions, the minimumposition, the detected current position, the target position, and themaximum lower offset position, and for providing an actuating signal tothe plurality of actuators and a directional rotation signal to thedrive motor.
 17. The method of claim 16, wherein the cleaning cyclefurther includes rotating the drive motor in a second rotationaldirection to move the plurality of movable cleaning devices in a secondlongitudinal direction.
 18. The method of claim 17, wherein the targetposition that is stored is updated after every cleaning cycle hascompleted.
 19. The method of claim 18, further comprising a hydraulicsystem for actuating the drive frame actuators.
 20. The method of claim19, further including stopping the drive motor and setting a pressurerelief valve in the hydraulic system to a minimum preload pressure uponsensing completion of the cleaning cycle, wherein the pressure reliefvalve is in fluid communication with the plurality of drive frameactuators.